tracing with sc_trace

[hakimelectronics]

Hi,
I am getting errors like below:

Trace ERROR:
No traces can be added once simulation has started.
To add traces, create a new vcd trace file.

Code of memory.cpp corresponding to error:

Memory::Memory(sc_core::sc_module_name name, unsigned int size)
    : sc_module(name), m_size(size)
{
    tf = sc_core::sc_create_vcd_trace_file("trace_data1"); // tracing, trace file creation
    tf->set_time_unit(10, sc_core::SC_US);
    storage = new ensitlm::data_t[size/sizeof(ensitlm::data_t)];
}

// Destructor
Memory::~Memory()
{
// close trace file
    sc_close_vcd_trace_file(tf);
    delete [] storage;
}

// Read transactions
tlm::tlm_response_status Memory::read(ensitlm::addr_t a, ensitlm::data_t& d)
{
     // Check if the address is within memory bounds

        if (a >= m_size)
    {
        
        sleep(5);
        return tlm::TLM_ADDRESS_ERROR_RESPONSE;
    }
        else
    {
        d = storage[a/sizeof(ensitlm::data_t)];

        sc_trace(tf, d ,"d");
             
        return tlm::TLM_OK_RESPONSE;
    }
}

// Write transactions
tlm::tlm_response_status Memory::write(ensitlm::addr_t a, ensitlm::data_t d)
{
        // Check if the address is within memory bounds
        if (a >= m_size)
    {
        
        sleep(5);
        return tlm::TLM_ADDRESS_ERROR_RESPONSE;
    }
        else
    {

        storage[a/sizeof(ensitlm::data_t)] = d;

        return tlm::TLM_OK_RESPONSE;
    }
}

code of memory.h :

SC_MODULE(Memory)
{
        ensitlm::target_socket<Memory> target;

     sc_core::sc_trace_file *tf;  

        Memory(sc_core::sc_module_name name, unsigned int size);

        ~Memory();
   
        tlm::tlm_response_status
        read(ensitlm::addr_t a, ensitlm::data_t& d);

        tlm::tlm_response_status
        write(ensitlm::addr_t a, ensitlm::data_t d);
    

private:

        unsigned int m_size;
public:
        /* The loader must have access to the storage */
        ensitlm::data_t* storage;

};

#endif

Please tell me the reasons behind these errors

 

 

Regards

 

Hakimelectronics

 

[Philipp A Hartmann]

Hakim,
 

Trace ERROR:
No traces can be added once simulation has started.
To add traces, create a new vcd trace file.

 
 Well, the reason for this error is the call to "sc_trace" inside your function, i.e. during the simulation.

 

In order to trace the data values, you should add a member variable to your memory and add it to the trace file within the constructor.  Something like:

SC_MODULE(Memory)
{
  // ...
private:
  ensitlm::data_t data_trace;
};

In the constructor, you then register the variable for tracing:

Memory::Memory( ... )
  : ...
{
    // ...
    sc_trace(tf, data_trace ,"d");
}

And in the "read" function, you update the "data_trace" variable:

tlm::tlm_response_status Memory::read(ensitlm::addr_t a, ensitlm::data_t& d)
{
  // instead of "sc_trace(...)"
  data_trace = d;
}

Hope that helps,
  Philipp

 

[hakimelectronics]

It works fine! thanks Philipp